The most common target for mutations in tumors is the p53 gene. The fact that around half of all human tumors carry mutations in this gene is solid testimony as to its critical role as tumor suppressor. p53 halts the cell cycle and/or triggers apoptosis in response to various stress stimuli, including DNA damage, hypoxia, and oncogene activation (Ko and Prives, 1996; Sherr, 1998). Upon activation, p53 initiates the p53-dependent biological responses through transcriptional transactivation of specific target genes carrying p53 DNA binding motifs. In addition, the multifaceted p53 protein may promote apoptosis through repression of certain genes lacking p53 binding sites and transcription-independent mechanisms as well (Bennett et al., 1998; Gottlieb and Oren, 1998; (Ko and Prives, 1996). Analyses of a large number of mutant p53 genes in human tumors have revealed a strong selection for mutations that inactivate the specific DNA binding function of p53; most mutations in tumors are point mutations clustered in the core domain of p53 (residues 94-292) that harbours the specific DNA binding activity (Béroud and Soussi, 1998).
Both p53-induced cell cycle arrest and apoptosis could be involved in p53-mediated tumor suppression. While p53-induced cell cycle arrest could conceivably be reversed in different ways, p53-induced cell death would have advantage of being irreversible. There is indeed evidence from animal in vivo models (Symonds et al., 1994) and human tumors (Bardeesy et al., 1995) indicating that p53-dependent apoptosis plays a major role in the elimination of emerging tumors, particularly in response to oncogenic signaling. Moreover, the ability of p53 to induce apoptosis often determines the efficacy of cancer therapy (Lowe et al., 1994). Taking into account the fact that more than 50% of human tumors carry p53 mutations, it appears highly desirable to restore the function of wild type p53-mediated growth suppression to tumors. The advantage of this approach is that it will allow selective elimination of tumor cells, carrying mutant p53. Tumor cells are particularly sensitive to p53 reactivation, supposedly for two main reasons. First, tumor cells are sensitized to apoptosis due to oncogene activation (reviewed in (Evan and Littlewood, 1998)). Second, mutant p53 proteins tend to accumulate at high levels in tumor cells. Therefore, restoration of the wild type function to the abundant and presumably “activated” mutant p53 should trigger a massive apoptotic response in already sensitized tumor cells, whereas normal cells that express low or undetectable levels of p53 should not be affected. The feasibility of p53 reactivation as an anticancer strategy is supported by the fact that a wide range of mutant p53 proteins are susceptible to reactivation. A therapeutic strategy based on rescuing p53-induced apoptosis should therefore be both powerful and widely applicable.
It may be shown that malfunctioning of the p53 pathway is generally involved in a number of diseases, such as those enumerated herein above. Indeed, in addition to hyperproliferative diseases, such as cancer, various authors have shown the involvement of deficient p53 functioning in a number of other disease states, e.g. autoimmune diseases and cardiac diseases.
Thus, in an article by Mountz et al. (1994) it is stated that human autoimmune diseases share the common feature of an imbalance between the production and destruction of various cell types including lymphocytes (SLE), synovial cells (RA), and fibroblasts (scleroderma). Oncogenes, including bcl-2, p53, and myc, that regulate apoptosis are also expressed abnormally. According to the authors, specific therapies that induce apoptosis without incurring side effects should improve treatment of autoimmune disease.
Bonafe M et al. (2004) present data suggesting that p53 codon 72 polymorphism contributes to a genetically determined variability in apoptotic susceptibility among old people, which has a potentially relevant role in the context of an age-related pathologic condition, such as myocardial ischaemia.
Okuda et al. (2003) present results suggesting that p53 may be involved in the regulatory process of experimental autoimmune encephalomyelitis (EAE) through the control of cytokine production and/or the apoptotic elimination of inflammatory cells. EAE as a model for autoimmune inflammatory diseases of the central nervous system (CNS) is a widely used model for the human disease multiple sclerosis.
Taken together, these findings suggest that pharmacological restoration of p53 function would be beneficial in a number of disorders and diseases.
The present inventors have found that the compound PRIMA-1 (i.e. 2,2-bis(hydroxymethyl)-1-azabicyclo[2.2.2]octan-3-one) (disclosed in WO 02/24692), is able to induce apoptosis of cells carrying mutant p53. Later they also found some analogues to Prima-1 that showed similar results (disclosed in WO 03/070250). Nonetheless, there still remains a general need of compounds having activity in the treatment of disorders and diseases related to p53 malfunctioning. Preferably, such compounds should have improved pharmacokinetic and pharmacodynamic properties. One main objective of the present invention is to provide such compounds.
The present inventors surprisingly have found several azabicyclooctan-3-one derivatives showing high activity in the treatment of disorders and diseases related to p53 malfunctioning. They not only show high potency, but they are also believed to have very favourable ADME properties due to their higher cLogP value which will allow a high cellular uptake. Several of the analogs could also be considered as prodrugs to Prima-1.
The azabicyclooctan-3-one derivatives of the invention are considered potentially useful in the treatment of hyperproliferative diseases, autoimmune diseases and heart diseases and especially in the treatment of disorders wherein malfunctioning of the p53 pathway may be involved, and this discovery forms the basis of the present invention. Furthermore, the compounds in the present invention are believed to have additional effects that are positive for the treatment of the above mentioned disorders, such as will be further discussed herein below.
2-Substituted 3-quinuclidinones have been described earlier in biological context but not in the above-mentioned therapeutic areas. Thus, 2-[N′—(O-alkoxyphenyl)piperazinomethyl]-3-quinuclidinones (Biel et al. U.S. Pat. No. 3,598,825) have been described as nervous system depressants and amine-substituted 2-methylene 3-quinuclidinones have been described as anti-bacterial agents (Elkin et al. U.S. Pat. No. 3,726,877) and antidepressant agents (Biel et al. U.S. Pat. No. 3,462,442).
Biel et al., in U.S. Pat. No. 3,384,641, describe a method wherein 2-methylene-3-quinuclidinone is reacted with amines to form intermediates which upon heating could release the amines. The intermediates thus are used for purification of amines.